The present invention relates to an improvement in devices for winding a fabric (woven, knitted . . . fabric) on an appropriate support mandrel during the different phases of manufacture of said fabric (weaving, knitting, dyeing, finishing, . . . ).
It relates more particularly to a winder device adaptable on warp knitting machines (Raschel knitting machines), but it is obvious that this is not limiting and that it may be used in other domains where similar problems are raised, for example on weaving looms.
Up to the present time, the winding of the knit as it leaves the machine poses numerous problems, being given that it is necessary to maintain the knit under constant tension if it is desired to avoid defects and that it is sought more and more to form rolls of knit of large diameter in order to reduce stops in production and to obtain cuts of considerable length.
In general, the knit produced is wound on a tubular support or mandrel which facilitates subsequent manipulations.
Up to the present time, two techniques are employed for winding the knit as it leaves the machine.
The first of these techniques consists in having an axial drive of the support mandrel, the speed of drive of said mandrel being modified as the diameter of the winding increases so as to have a constant linear speed and a likewise constant tension.
The second consists in effecting the drive by means of two bearing rollers on which rests the wind of knitted fabric (carrying tangential winding).
In both cases, numerous problems are raised when it is desired to obtain large-diameter windings, these problems being further accentuated when the knit made is an elastic knit.
In fact, in both cases, the two factors: traction and pressure, may produce surface defects in the knit.
Moreover, the traction does not allow a sufficient relaxation of the elastic knits, hence the necessity of effecting a tensionless winding which generally poses the problem of the correct unwinding of the selvedges.
Furthermore, in the case of tangential winding, the pressure or crushing due to the increase in the weight of the piece, particularly when it is desired to have windings weighing more than one hundred kilos, does not make it possible to have a relaxation of the knit already wound.
Finally, in both cases, the removal of the roll formed as well as the positioning of the support mandrel requires manipulations which are all the more delicate to carry out as the piece is heavy.
U.S. Pat. No. 4,139,166 also discloses a device for winding a fabric in which the material is wound on a support mandrel, the drive being obtained by tangential contact with driving cylinders disposed above the winding. According to the solution described in that Patent, the driving cylinders are maintained under pressure against the fabric and are driven at different speeds, this in order to obtain a very close winding. Such an installation can therefore not be used when it is desired to wind fragile materials such as knits, being given that, in that case, defects would be produced on this material, in particular watering effects. Furthermore, the system for communicating the pressure to the driving cylinders is essentially constituted by an articulated arm associated with a jack which, on the one hand, therefore necessarily limits the diameter of the winding capable of being formed and, on the other hand, considerably increases the ground surface of the installation.
The device according to the invention overcomes the drawbacks of the prior known solutions and in particular makes it possible to produce a winding which is independent of the weight of the piece, to considerably increase the diameter (therefore the weight) of the winding formed as well as to facilitate positioning and removal of the roll of material formed. Moreover, the device according to the invention makes it possible to avoid creating surface defects on the material and to effect a tensionless winding, particularly in the case of elastic knits, and this whilst having a correct unwinding of the selvedges.
The invention therefore generally relates to a device for winding a fabric (in particular a knitted fabric) during the different phases of its manufacture, device whereby the material is wound on a support mandrel, drive being obtained by tangential contact with driving cylinders disposed above the winding, the device according to the invention being characterized in that the driving cylinders are at least two in number and are disposed symmetrically on either side of a vertical plane passing through the axis of said winding, these cylinders rotating at the same speed, exerting a constant pressure on the winding and being mounted on a support capable of sliding along vertical uprights, disposed on each side of the machine, and this as the diameter increases.
In a preferred embodiment of the invention, the material is wound on a mandrel supported by a carriage (or container) adapted to serve for transport and for storage.
Furthermore, the winder according to the invention may be adapted either at the front or at the rear of the machine. The driving cylinders may be driven by an independent motor or directly from the machine. In the former case, the speed may be adjusted by means of a potentiometer or a reduction gear and, in the latter, by a gear box. The winder is, of course, disengageable with respect to the machine.
The device according to the invention is associated with means for modifying the pressure exerted by the driving cylinders on the winding.
Furthermore, the device according to the invention also comprises an element for ensuring unwinding of the selvedges, this element being, in one embodiment, constituted by an assembly comprising a rotating brush and an expander bar.